[GreenKeys] Model 19 Power Supplies

[Paul Heller]

Well perhaps I’ve lived too dangerously and it is time to change. I have two model 19s, one is Bell and one is Navy. I’ve never powered on the Navy unit, but have occasionally used the Bell unit.  Now you guys have me worried.

Paul
W2TTY

> On Jan 13, 2020, at 9:29 PM, Bruce Gentry via GreenKeys <greenkeys at mailman.qth.net> wrote:
> 
> A resistor to imitate the forward drop of a selenium rectifier will work well only with a fairly constant load. The punch magnets in a 19 intermittently draw a good bit of current,� adjusting transformer taps (if there are any) or adding a bucking transformer to the circuit to reduce the voltage going into the rectifier� would be� far better. Be sure to use silicon diodes with at least a 1000 volt rating, the transient voltages in the punch magnet circuit can be quite high even with the snubber circuit. One great advantage of selenium rectifiers is their tolerence for transients and momentary overloads. They will endure a lot of abuse and survive. 
> 
> ���� Bruce Gentry, KA2IVY
> 
> 
> On 1/13/20 10:48 PM, w9ddd at tapr.org <mailto:w9ddd at tapr.org> wrote:
>> A long discussion about replacing selenium with silicon diodes here:
>> https://antiqueradios.com/forums/viewtopic.php?t=305477 <https://antiqueradios.com/forums/viewtopic.php?t=305477>
>> 
>> My take away is you can approximate by putting a 100-200 ohm resistor in series with the silicon.
>> 
>> John, W9DDD
>> 
>> 
>> On Jan 13, 2020, at 4:46 PM, E. <hanyou at xsmail.com <mailto:hanyou at xsmail.com>> wrote:
>> 
>>> 
>>> That�s one of the reasons why I have two power supplies on mine� one for the loop and the second for the DC punch side ;) . �Overkill, but better safe than sorry :) ~
>>> 
>>> 
>>>> On Jan 13, 2020, at 4:39 pm, Jim Cooper <jim.w2jc at gmail.com <mailto:jim.w2jc at gmail.com>> wrote:
>>>> 
>>>> On 13 Jan 2020 at 15:44, Jim Haynes wrote:
>>>> 
>>>>> If you're using that rectifier for
>>>>> loop power as well as for running the
>>>>> punch you'd need to adjust the loop
>>>>> current because of the higher voltage. 
>>>> 
>>>> Keep in mind, also, that the reason for the 
>>>> regulation in the case of the Model 19 is 
>>>> that the punch solenoid takes a LOT of current 
>>>> in sharp, irregular bursts ... which could do lots 
>>>> of mess with the loop current if not regulated. 
>>>> 

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